1. Field of the Invention
The present invention relates generally to semiconductor integrated circuits, and more specifically to formation of a bond pad structure for such circuits.
2. Description of the Prior Art
After an integrated circuit device has completed the fabrication process, it is usually assembled into a package to be utilized on a printed circuit board as part of a larger circuit. In order for the inner leads of the package to make electrical contact with the bonding pads of the fabricated device, a metal bond is formed at the bonding pad of the device with a lead extending to the inner lead of the package lead frame.
During the formation of a bond, bond pad lift off may occur. This problem results when the large, heavy bond is placed on top of layers which have not formed a strong adhesion to the underlying layers. During formation of aluminum interconnect, it is common to form an underlying barrier layer of a material such as titanium nitride. This barrier layer is utilized to prevent the aluminum from spiking into any underlying conductive layers during later fabrication steps. However, the barrier layer, which is usually titanium nitride, does not form a strong adhesion to the oxide underlying the bond pad, and may separate during the bonding process.
Therefore, it would be desirable to provide a method for forming an improved bond pad structure whereby a bond may be formed at a bonding pad which is resistant to layer separation at the bond pad.